The present invention relates to a thermal management system for an electrochemical engine in a vehicle.
Thermal management of an electrochemical engine presents several important considerations and challenges as compared to a conventional internal combustion engine. First, in an internal combustion engine, waste heat is managed about equally through both an exhaust gas stream and through a flow of air-cooled engine coolant. In comparison, an electrochemical engine manages most of its waste heat through air-cooled engine coolant. Second, an internal combustion engine typically operates at 120xc2x0 C., where an electrochemical engine operates at the lower temperature of 80xc2x0 C. Therefore the heat transfer between the coolant and air in a thermal management system of an electrochemical engine is about one-half that of an internal combustion engine due to the smaller temperature differential between the waste heat and ambient at 38xc2x0 C. These two considerations in combination may necessitate a threefold increase in the cooling air flow rate through the radiator and an order of magnitude increase in its associated fan power. A thermal management system meeting such requirements may be too large to be packaged in the conventional location at the front of the vehicle.
The present invention is directed to a thermal management system for an electrochemical engine in a vehicle. In this thermal management system, a radiator and associated fan are packaged in the rear of the vehicle, independent of the packaging location of the electrochemical engine. The rear of the vehicle may have more available packaging volume to accommodate a large face area radiator, which allows high air flow with lower fan power requirements.
To take advantage of the surface area available in the rear of the vehicle, the radiator may be mounted flat, horizontally behind the rear axle between the rear frame rails. Air inlet ducts are designed to preserve cargo and passenger compartment volume and to provide smooth ductwork to the radiator such as by louvered panels or air scoops near the rear windows. The fans may be mounted to either force air in or pull air through the radiator.
Akin to the first embodiment, the radiator is packaged to take advantage of the surface area available in the rear of the vehicle. Here the radiator is mounted at an incline between the roof inner and outer panels. Air inlets in the roof outer panel draw air into an inlet air duct, forward of the radiator, allowing air to flow through the radiator and exit an air duct outlet rearward of the radiator.
The thermal management system of the present invention provides sufficient air cooling of the fuel cell stack-heated coolant, while having minimal impact on overall vehicle packaging.